int LED1 = 0;  // Use pin 2 for LED1
int LED2 = 1;  // Use pin 3 for LED2
int LED3 = 2;  // Use pin 4 for LED3
int LED4 = 3;  // Use pin 5 for LED4
int LED5 = 4;  // Use pin 6 for LED5
int LED6 = 5;  // Use pin 7 for LED6
int LED7 = 6;  // Use pin 8 for LED7
int LED8 = 7;  // Use pin 9 for LED8
int BUTTON_PIN = 8;  // Use pin 10 for the button

void setup() {
    // Set LED pins as outputs
    pinMode(LED1, OUTPUT);
    pinMode(LED2, OUTPUT);
    pinMode(LED3, OUTPUT);
    pinMode(LED4, OUTPUT);
    pinMode(LED5, OUTPUT);
    pinMode(LED6, OUTPUT);
    pinMode(LED7, OUTPUT);
    pinMode(LED8, OUTPUT);
    
    // Set the button pin as input
    pinMode(BUTTON_PIN, INPUT_PULLUP);  // Use internal pull-up resistor
}

void loop() {
    // Check if the button is pressed
    if (digitalRead(BUTTON_PIN) == HIGH) {  // Button is pressed (LOW with pull-up)

        // Shift LEDs from left to right
        for (int i = LED1; i <= LED8; i++) {
            digitalWrite(i, HIGH);  // Turn on LED
            delay(250);             // 250 ms delay
            digitalWrite(i, LOW);   // Turn off LED
        }

        // Shift LEDs from right to left
        for (int i = LED8; i >= LED1; i--) {
            digitalWrite(i, HIGH);  // Turn on LED
            delay(250);             // 250 ms delay
            digitalWrite(i, LOW);   // Turn off LED
        }
    }
}